There is a known biological information detection apparatus that detects biological information, such as a pulse wave of a person. PTL 1 and PTL 2 each disclose related art of a pulse rate meter, which is an example of the biological information detection apparatus. The pulse rate meter is worn, for example, around an arm, a wrist, a finger, or any other portion of a human body and detects beating resulting from the heartbeat of the human body to measure the pulse rate.
Each of the pulse rate meters disclosed in PTL 1 and PTL 2 is a photoelectric pulse rate meter, and a light detection unit thereof includes a light emitter that emits light toward a subject that is an object of interest and a light receiver that receives light from the subject (light containing biological information). The pulse rate meter detects a change in the amount of blood flow in the form of a change in the amount of received light to detect a pulse wave. PTL 1 discloses a pulse rate meter of a type worn around a wrist, and PTL 2 discloses a pulse rate meter of a type worn around a finger. Further, PTL 3 discloses a light sensor including a light receiver provided with a light blocking member.